Lube Basestock With Improved Low Temperature Properties

ABSTRACT

This invention relates to basestocks and base oils with improved low temperature properties and formulated lubricant compositions or functional fluids created by blending at least one such lube basestock with at least one component selected from dispersants, detergents, wear inhibitors, antioxidants, rust inhibitors, demulsifiers, extreme pressure agents, friction modifiers, multifunction additives, viscosity index improvers, pour point depressants, and foam inhibitors. In particular the invention relates to dewaxed lube basestocks having a Free Carbon Index of less than 4.3 and an Epsilon Carbon mole % of less than 14%. Formulated engine oils using such dewaxed basestocks exhibit improved low temperature properties as may be measured by the Mini Rotary Viscometer test.

FIELD OF THE INVENTION

This invention relates to base stocks and base oils with improved lowtemperature properties and formulated lubricant compositions orfunctional fluids created by blending at least one such lube basestockwith at least one component selected from dispersants, detergents, wearinhibitors, antioxidants, rust inhibitors, demulsifiers, extremepressure agents, friction modifiers, multifunction additives, viscosityindex improvers, pour point depressants, and foam inhibitors.

BACKGROUND OF THE INVENTION

Historically, lubricating oil products for use in many applications haveused additives to impart specific properties to the finished oils toaugment the properties of the basestocks used to prepare the finishedproducts. With the advent of more demanding test requirements, theperformance requirements for the basestocks themselves have increased.The American Petroleum Institute (API) definition of a Group IIbasestock is one that has a saturates content of at least 90%, a sulfurcontent of 0.03 wt. % or less and a viscosity index (VI) between 80 and120. Similarly, the API definition of a Group III basestock is one thathas a saturates content of at least 90%, a sulfur content of 0.03 wt %or less, and a viscosity index of 120 or greater. Currently, there is atrend in the lube oil market to use increasing amounts of Group II andIII basestocks to replace the traditionally used Group I basestocks inorder to meet the demand for higher quality finished lubricants and meetmore stringent requirements for improved oxidative stability, reduceddeposits, reduced evaporative emissions, superior low temperatureperformance, controlled wear performance, improved fuel economy, andcompatibility with aftertreatment devices.

While Group II and Group III basestocks provide some of the attributesdesired, further improvements in many properties, particularly lowtemperature quality, as well as combinations of properties, such assuperior low temperature fluidity at low product volatility, continue tochallenge the industry. Benefits in basestock low temperatureperformance would be beneficial for a wide range of formulatedlubricants and would be particularly advantageous for passenger vehiclecrankcase oils, automatic transmission fluids, automotive gear oils,hydraulic fluids, and commercial vehicle crankcase oils.

Low temperature quality for basestocks and base oils have historicallybeen controlled using bulk property measurements such as pour pointmeasured on the basestock, base oils, or formulated oil composition.However, small amounts of residual wax may not impact this bulk propertymeasurement and thus, small amounts of residual wax may go undetectedthrough this analysis. This small amount of residual wax, however, doesnegatively impact performance and can lead to issues such as crankcaseoil gelling and loss of fluidity. Operating an engine in this scenariocan lead to engine damage. Hence, the Mini-Rotary Viscometer (MRV) testwas established to protect engines under cold weather conditions. TheMRV test temperature is set by the Society of Automotive Engineers (SAE)J-300 Viscosity Classification system for each multigrade engine oilgrade.

To improve the low temperature performance as measured by the MRV orother tests sensitive to very small amounts of residual wax, refineriesutilitizing solvent dewaxing can dewax to lower pour points. While thiscan be somewhat effective, it may not be as effective as needed.Catalytic dewaxing, a relatively newer processing approach, is oftenmore effective than solvent dewaxing, especially for the light andmedium neutral stocks. However, many existing refineries in operationtoday utilize solvent dewaxing only and do not have a reactor availablefor catalytic dewaxing which often requires significant quantities ofhydrogen provided at high pressure.

As the demand for quality formulated lubricant oils continues toincrease, the search for better basestocks produced from new anddifferent processes, catalysts, and catalyst systems that exhibitimproved quality and performance at high activity and yield is acontinuous, ongoing exercise. Therefore, there is a need in the lube oilmarket to provide lube basestocks, that when formulated into a finishedoil, can help to meet the demand for improved low temperatureproperties.

SUMMARY OF THE INVENTION

This invention relates to basestocks with superior low temperatureproperties and formulated lubricant compositions or functional fluidscreated by blending at least one such lube basestock with at least onecomponent selected from dispersants, detergents, wear inhibitors,antioxidants, rust inhibitors, demulsifiers, extreme pressure agents,friction modifiers, multifunction additives, viscosity index improvers,pour point depressants, and foam inhibitors.

In particular the invention relates to a dewaxed lube basestock having aFree Carbon Index of less than 4.3 and an Epsilon Carbon mole % of lessthan 14%. In other embodiments it relates to dewaxed lube basestockshaving a Free Carbon Index of less than 4.3 and an Epsilon Carbon mole %of less than 14% or a dewaxed lube basestock having a Free Carbon Indexof less than 4.3 and an Epsilon Carbon mole % of less than 14%, or adewaxed lube basestock wherein the Pour Point is between −6° C. and −30°C.

In other embodiments the lube basestock is prepared by a processcomprising

-   a. solvent dewaxing a lube oil boiling range feedstream in a solvent    dewaxing stage operated under effective solvent dewaxing conditions    thereby producing at least a partially dewaxed fraction; and-   b. contacting said partially dewaxed fraction with a hydrodewaxing    catalyst in the presence of a hydrogen-containing treat gas in a    reaction stage operated under effective hydrodewaxing conditions    thereby producing a reaction product comprising at least a gaseous    product and liquid product, wherein said liquid product comprises a    dewaxed lube basestock. In other embodiments said hydrodewaxing    catalyst is selected from ZSM-5, ZSM-22, ZSM-23, ZSM-35, ZSM-48,    ZSM-57, Beta, SSZ-31, SAPO-11, SAPO-31, SAPO-41, MAPO-11. ECR-42,    fluorided alumina, silica-alumina, fluorided silica alumina,    synthetic Ferrierites, Mordenite, Offretite, Erionite, Chabazite,    and mixtures thereof under effective catalytic dewaxing conditions.

In yet other embodiments said hydrodewaxing catalyst comprises a zeoliteselected from ZSM-48, ZSM-22 and ZSM-23. In yet other embodiments saidhydrodewaxing catalyst further comprises at least one metalhydrogenation component, which is selected from Group VI metals, GroupVIII metals, or mixtures thereof and contains at least one Group VIIInoble metal.

Other embodiments of the invention relate to a formulated oilcomprising:

-   a. a major amount of at least one dewaxed lube basestock according    to the embodiments described above and,-   b. at least one component selected from dispersants, detergents,    wear inhibitors, antioxidants, rust inhibitors, demulsifiers,    extreme pressure agents, friction modifiers, multifunction    additives, viscosity index improvers, pour point depressants, and    foam inhibitors.

Other embodiments include an engine oil according to the aboveembodiments wherein said engine oil has a Mini Rotary Viscometerviscosity from about 10,000 cP to about 30,000 cP, or has a Mini RotaryViscometer viscosity from about 10,000 cP to about 25,000 cP, or has aMini Rotary Viscometer viscosity from about 12,000 cP to about 20,000cP.

In yet other embodiments the invention relates to an engine oilcomprising:

-   a) at least 60% by weight of the total composition of a dewaxed lube    basestock having a Free Carbon Index of from 3.0 to 4.3 and an    Epsilon Carbon mole % from 10.0% to 14.0% and wherein the kinematic    viscosity at 100° C. is between 3 cSt and 7 cSt, the Viscosity Index    is between 95 and 150, and the Pour Point is between −6° C. and −30°    C.-   b) at least one component selected from dispersants, detergents,    wear inhibitors, antioxidants, rust inhibitors, demulsifiers,    extreme pressure agents, friction modifiers, multifunction    additives, viscosity index improvers, pour point depressants, and    foam inhibitors, and    wherein the said engine oil has a Mini Rotary Viscometer viscosity    from about 10,000 cP to about 25,000 cP.

In yet other embodiments the invention relates to an engine oilcomprising:

-   a) at least 60% by weight of the total composition of a dewaxed lube    basestock having a Free Carbon Index of from 3.0 to 4.3 and an    Epsilon Carbon mole % from 10.0% to 14.0% and wherein the kinematic    viscosity at 100° C. is between 3 cSt and 7 cSt, the Viscosity Index    is between 95 and 150, and the Pour Point is less than −6° C. and    wherein said dewaxed lube basestock is prepared by a process    comprising-   (i) solvent dewaxing a lube oil boiling range feedstream in a    solvent dewaxing stage operated under effective solvent dewaxing    conditions thereby producing at least a partially dewaxed fraction;    and-   (ii) contacting said partially dewaxed fraction with a hydrodewaxing    catalyst in the presence of a hydrogen-containing treat gas in a    reaction stage operated under effective hydrodewaxing conditions    thereby producing a reaction product comprising at least a gaseous    product and liquid product, wherein said liquid product comprises a    dewaxed lube basestock.-   b) at least one component selected from dispersants, detergents,    wear inhibitors, antioxidants, rust inhibitors, demulsifiers,    extreme pressure agents, friction modifiers, multifunction    additives, viscosity index improvers, pour point depressants, and    foam inhibitors, and    wherein the said engine oil has a Mini Rotary Viscometer viscosity    from about 10,000 cP to about 25,000 cP.

In yet other embodiments the invention relates to an engine oilcomprising:

-   a) at least 60% by weight of the total composition of a dewaxed lube    basestock having a Free Carbon Index of from 3.0 to 4.3 and an    Epsilon Carbon mole % from 10.0% to 14.0% and wherein the kinematic    viscosity at 100° C. is between 3 cSt and 7 cSt, the Viscosity Index    is between 95 and 150, and the Pour Point is less than −6° C. and    wherein said dewaxed lube basestock is prepared by a process    comprising-   (i) solvent dewaxing a lube oil boiling range feedstream in a    solvent dewaxing stage operated under effective solvent dewaxing    conditions thereby producing at least a partially dewaxed fraction;    and-   (ii) contacting said partially dewaxed fraction with a hydrodewaxing    catalyst in the presence of a hydrogen-containing treat gas in a    reaction stage operated under effective hydrodewaxing conditions    thereby producing a reaction product comprising at least a gaseous    product and liquid product, wherein said liquid product comprises a    dewaxed lube basestock.-   b) at least one component selected from dispersants, detergents,    wear inhibitors, antioxidants, rust inhibitors, demulsifiers,    extreme pressure agents, friction modifiers, multifunction    additives, viscosity index improvers, pour point depressants, and    foam inhibitors, and    wherein the said engine oil has a Mini Rotary Viscometer viscosity    from about 10,000 cP to about 25,000 cP.

In yet other embodiments the invention relates to a method offormulating an engine oil comprising blending a dewaxed lube basestockas characterized in the previously described embodiments with at leastone component selected from dispersants, detergents, wear inhibitors,antioxidants, rust inhibitors, demulsifiers, extreme pressure agents,friction modifiers, multifunction additives, viscosity index improvers,pour point depressants, and foam inhibitors.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to basestocks and base oils with superior lowtemperature properties and formulated lubricant compositions orfunctional fluids created by blending at least one such lube basestockwith at least one component selected from dispersants, detergents, wearinhibitors, antioxidants, rust inhibitors, demulsifiers, extremepressure agents, friction modifiers, multifunction additives, viscosityindex improvers, pour point depressants, and foam inhibitors.

It should be noted that the terms “feedstock” and “feedstream” can beused interchangeably herein.

Tests used in describing lubricant compositions of this invention are:

-   (a) MRV viscosity measured by Mini-Rotary Viscometer Test (ASTM    D46S4);-   (b) CCS viscosity measured by Cold Cranking Simulator Test (ASTM    D5293);-   (c) Noack volatility (or evaporative loss) correlated from Simulated    Distillation by Gas Chromatography using ASTM D2887 or measured    directly by ASTM D5800;-   (d) Viscosity index (VI) measured by ASTM D2270;-   (e) Kinematic viscosity measured by ASTM D445-   (f) Pour point (ISL) as measured by ASTM D5950.

Lube basestocks in the present invention can also be described as thoselube basestocks having a Free Carbon Index (FCI) of less than 4.3,preferably less than 4.1 or from 3.0 to 4.3, preferably from 3.0 to 4.1,and an Epsilon Carbon content (mole %) of less than 14%, preferably lessthan 13.3. The FCI can be measured by the method described in, forexample, U.S. Pat. No. 6,676,827. The FCI is further explained asfollows. The basestock is analyzed by ¹³C NMR using a 400 MHzspectrometer. At this magnetic field strength, all normal paraffins withcarbon numbers greater than C₉ have only five non-equivalent NMRadsorptions corresponding to the terminal methyl carbons (alpha), aswell as methylenes from the second, third and fourth positions from themolecular ends (beta, gamma, and delta respectively), and the othercarbon atoms along the backbone which have a common chemical shift(epsilon). For normal paraffins, the intensities of the alpha, beta,gamma and delta are equal and the intensity of the epsilon depends onthe length of the molecule. Similarly, the side branches on the backboneof an iso-paraffin have distinctive chemical shifts; the presence of aside chain causes a measurable shift at the tertiary carbon (branchpoint) on the backbone to which it is anchored. Further, it alsoperturbs the chemical sites within three carbons from this branch pointimparting unique chemical shifts (alpha, beta, and gamma).

The Free Carbon Index (FCI) is then defined as the product of the carbonmole percent of epsilon methylenes measured from the overall carbonspecies in the ¹³C NMR spectrum of a basestock and, the average carbonNumber (CN) of the basestock as calculated from the equation below:

${CN} = \frac{200}{\alpha - {PBu} + {TMe} + {TEt} + {TPr} + {TBu}}$

where the values for α, PBu, TMe, TEt, TPr, and TBu are in units ofcarbon mole percent.

For example, the FCI can be further explained as follows. Sinceparticular structural types have characteristic spectral features, theFCI method of data processing provides a description of the averagemolecular structure of the normal and branched paraffins in a sample.Among the figures of merit that result from this analysis are theaverage carbon number of the sample (CN), the number of side chains(NS), and the free carbon index (FCI). The FCI is defined as the numberof carbons that are more than four carbons away from a chain end or morethan three carbons away from a branch point on a hydrocarbon backbone;these carbons are also labeled as epsilon, (“ε”) in the drawing below.In practice, FCI represents the product of the CN and the molepercentage contribution of epsilon to the NMR spectrum.

As an example, the above structure illustrates some of the nomenclatureassociated with this analysis. For this illustrative molecule, CN=26,NS=2, and FCI=8. While the above molecule represents a pure compound,lube basestocks consist of extremely complex mixtures of molecules.However, since the structural components such as alpha, beta, gamma,etc. listed above (in addition to other structural pieces not includedabove) exhibit characteristic and repeatable spectral signals, NMRallows for a statistically averaged structural characterization of theensemble. Epsilon and FCI represent the most pertinent features of theNMR analysis.

As stated above, the formulated lubricant compositions of the instantinvention also comprise at least one component selected fromdispersants, detergents, wear inhibitors, antioxidants, rust inhibitors,demulsifiers, extreme pressure agents, friction modifiers, multifunctionadditives, viscosity index improvers, pour point depressants, and foaminhibitors. The at least one component selected from the above describedlist, can be any of these components known. For example, dispersantssuitable for use in the present formulated engine oils can be anydispersants used in formulated engine oils; detergents suitable for usein the present lubricant products can be selected from any detergentsused in formulated oils, etc.

The formulated engine oils of the instant invention can also bedescribed as possessing a Mini Rotary Viscometer (“MRV”) viscosity lessthan 30,000 cP, preferably from about 10,000 cP to about 30,000 cP, morepreferably from about 10,000 cP to about 25,000 cP and most preferablyfrom about 12,000 cP to about 20,000 cP.

The lube oil basestock can be produced by a process comprising solventdewaxing a lube oil boiling range feedstream under conditions effectiveat producing at least a partially dewaxed fraction. The partiallydewaxed fraction is then contacted with a catalytic hydrodewaxingcatalyst in the presence of hydrogen containing treat gas in a reactionstage operated under effective catalytic hydrodewaxing conditionsthereby producing a reaction product comprising at least a gaseousproduct and liquid product comprising a lube basestock. A lube oilboiling range feed stream is first contacted in a first reaction stagewith a hydroprocessing catalyst, in the presence of a hydrogencontaining treat gas, under effective hydroprocessing conditions therebyproducing at least a liquid hydroprocessed lube oil product. Thehydroprocessed lube oil product is then conducted to the solventdewaxing zone. Also, in some embodiments of the instant invention,separation stages are employed to separate gaseous and liquid reactionproducts, dewaxing solvent from the dewaxed product, etc.

As stated above, the formulated oils comprise at least one lube oilbasestock, and the lube oil basestocks suitable for use as a componentin the presently claimed formulated oils are produced by a specificprocess. Lube oil boiling range feedstocks suitable for use in creatingthe at least one lube oil basestock are wax-containing feeds that boilin the lubricating oil range. These lube oil boiling range feedstockstypically having a 10% distillation point greater than 650° F. (343°C.), measured by ASTM D 86 or ASTM 2887, and are derived from mineralsources, synthetic sources, or a mixture of the two. Non-limitingexamples of suitable lubricating oil feedstocks include those derivedfrom sources such as oils derived from solvent refining processes suchas raffinates, partially solvent dewaxed oils, deasphalted oils,distillates, vacuum gas oils, coker gas oils, slack waxes, foots oilsand the like, dewaxed oils, Fischer-Tropsch waxes and GTL materials.

GTL materials are materials that are derived via one or more synthesis,combination, transformation, rearrangement, and/ordegradation/deconstructive processes from gaseous carbon-containingcompounds, hydrogen-containing compounds, and/or elements as feedstockssuch as hydrogen, carbon dioxide, carbon monoxide, water, methane,ethane, ethylene, acetylene, propane, propylene, propyne, butane,butylenes, and butynes. GTL base stocks and base oils are GTL materialsof lubricating viscosity that are generally derived from hydrocarbons,for example waxy synthesized hydrocarbons, that are themselves derivedfrom simpler gaseous carbon-containing compounds, hydrogen-containingcompounds and/or elements as feedstocks. GTL base stocks and base oilsinclude wax isomerates, comprising, for example, hydroisomerized orisodewaxed synthesized waxy hydrocarbons, hydroisomerized or isodewaxedFischer-Tropsch (F-T) material (i.e., hydrocarbons, waxy hydrocarbons,waxes and possible analogous oxygenates), preferably hydroisomerized orisodewaxed F-T waxy hydrocarbons or hydroisomerized or isodewaxed F-Twaxes, hydroisomerized or isodewaxed synthesized waxes, or mixturesthereof. The term GTL base stocks and base oil further encompass theaforesaid base stock and base oils in combination with otherhydroisomerized or isodewaxed materials comprising for example,hydroisomerized or isodewaxed mineral/petroleum-derived hydrocarbons,hydroisomerized or isodewaxed waxy hydrocarbons, or mixtures thereof,derived from different feed materials including, for example, waxydistillates such as gas oils, waxy hydrocracked hydrocarbons,lubricating oils, high pour point polyalphaolefins, foots oil, normalalpha olefin waxes, slack waxes, deoiled waxes, and microcrystallinewaxes.

These lube oil boiling range feedstocks suitable may also have highcontents of nitrogen- and sulfur-contaminants. Sulfur and nitrogencontents may be measured by standard ASTM methods D5453 and D4629,respectively.

The process used to produce lube basestocks suitable for use in thepresent formulated oils involves solvent extracting a lube oil boilingrange feedstock in a solvent dewaxing stage operated under effectivesolvent dewaxing conditions thereby producing at least a partiallydewaxed fraction. The solvent dewaxing step typically involves mixing alube oil boiling range feedstock with a dewaxing solvent at atmosphericpressure, separating precipitated wax and recovering solvent forrecycling. During the solvent dewaxing step, the lube oil boiling rangefeedstock is mixed with chilled solvent to form an oil-solvent solutionand precipitated wax is thereafter separated by, for example,filtration. The temperature and solvent are selected so that the oil isdissolved by the chilled solvent while the wax is precipitated. Thus,one embodiment of the process used to create lube basestocks suitablefor use herein involves separating, by any suitable separation means,the solvent and partially dewaxed fraction, recovering the partiallydewaxed fraction and conducting the partially dewaxed fraction to acatalytic hydrodewaxing reaction stage. It should be noted that becausesolvent dewaxing typically occurs at atmospheric pressure, it may benecessary to pressurize the partially dewaxed fraction prior to thecatalytic dewaxing step.

A particularly suitable solvent dewaxing step involves the use of acooling tower where solvent is prechilled and added incrementally atseveral points along the height of the cooling tower. The lube oilboiling range feedstream-solvent mixture is agitated during the chillingstep to permit substantially instantaneous mixing of the prechilledsolvent with the lube oil boiling range feedstream. The prechilledsolvent is added incrementally along the length of the cooling tower soas to maintain an average chilling rate at or below 10° F./minute,usually between about 1 to about 5° F./minute. The final temperature ofthe lube oil boiling range feedstream-solvent/precipitated wax mixturein the cooling tower will usually be between 0 and 50° F. (−17.8 to 10°C.). The mixture may then be sent to a scraped surface chiller toseparate precipitated wax from the mixture.

Generally, effective solvent dewaxing conditions will include thatamount of solvent that when added to the lube oil boiling rangefeedstream will be sufficient to provide a liquid/solid weight ratio ofabout 5/1 to about 20/1 at the dewaxing temperature and a solvent/oilvolume ratio between 1.5/1 to 5/1. The solvent dewaxing of the lube oilboiling range feedstream typically results in a partially dewaxedfraction having a pour point from about +30° C. to about −20° C. Thebenefits observed were seen whether the solvent dewaxing step was verymild and removed very little wax leaving a higher intermediate pourpoint stream or the solvent dewaxing step was more severe and removedmost of the wax leaving a lower intermediate pour point stream.

Representative dewaxing solvents are aliphatic ketones having 3-6 carbonatoms such as methyl ethyl ketone and methyl isobutyl ketone, lowmolecular weight hydrocarbons such as propane and butane, and mixturesthereof. The solvents may be mixed with other solvents such as benzene,toluene or xylene. Further descriptions of solvent dewaxing processuseful herein are disclosed in U.S. Pat. Nos. 3,773,650 and 3,775,288,which are incorporated herein in their entirety.

The partially dewaxed fraction from the solvent dewaxing step issubjected to a catalytic dewaxing step to remove at least a portion ofany wax remaining in the partially dewaxed fraction. This step iscommonly used to further lower the pour point of the partially dewaxedfraction. The sequence of solvent dewaxing followed by catalyticdewaxing is designated as trim dewaxing when the catalytic dewaxingstage removes and isomerizes a relatively small amount of wax as opposedto the solvent dewaxing step.

During the catalytic hydrodewaxing step, the partially dewaxed fractionis contacted with a catalytic hydrodewaxing catalyst in the presence ofa hydrogen containing treat gas in a reaction stage operated undereffective catalytic hydrodewaxing conditions. Effective catalytichydrodewaxing conditions as used herein includes temperatures betweenabout 200° C. to about 350° C., preferably about 250° C. to about 325°C., more preferably 250 to 320° C., pressures between about 2,860 toabout 20,786 kPa (about 400 to about 3,000 psig), preferably about 4,238to about 17,338 kPa (about 600 to about 2,500 psig), preferably about4,238 to about 10,443 kPa (about 600 to about 1,500 psig) hydrogen treatgas rates of about 89 to about 890 m³/m³ (about 500 to about 5,000 SCFH₂/B), preferably about 107 to about 445 m³/m³ (about 600 to about 2,500SCF H₂/B), and liquid hourly space velocities (“LHSV”) of about 0.1 toabout 10 V/v/hr, preferably about 0.1 to about 5 V/V/hr, more preferablyabout 0.5 to about 2 V/V/hr. Operating the catalytic hydrodewaxing underthese narrow, less severe, catalytic hydrodewaxing conditions, thecatalytic hydrodewaxing stage reaction stage operates to convert traceparaffins that impair low temperature properties of the partiallydewaxed fraction at a low yield loss while still maintaining the keylube basestock properties such as pour point, viscosity, viscosity index(“VI”), and volatility of the partially dewaxed fraction resulting fromthe solvent-dewaxing operation described herein. Therefore, effectivecatalytic hydrodewaxing conditions, as used herein, are to be consideredthose catalytic hydrodewaxing conditions as described above that resultin a lube basestock having a VI within about 0 to about 30 points of thepartially dewaxed fraction, a pour point within about 0 to about −50° C.of the partially dewaxed fraction, and in a yield loss of about 0 toabout 20 wt. In all cases the effective catalytic hydrodewaxing stagefollows the solvent dewaxing stage.

Catalytic hydrodewaxing catalysts suitable for use in the trim dewaxingstep may be either crystalline or amorphous. Amorphous catalytichydrodewaxing catalysts include alumina, fluorided alumina,silica-alumina, fluorided silica-alumina. Such catalysts are describedfor example in U.S. Pat. Nos. 4,900,707 and 6,383,366.

Crystalline materials are molecular sieves that contain at least one 10or 12 ring channel and may be based on aluminosilicates (zeolites) or onaluminophosphates such as silicoaluminophosphates (SAPOs) and MAPOs.Molecular sieves suitable for use herein contain at least one 10 or 12channel. Examples of such zeolites include ZSM-22, ZSM-23, ZSM-35,ZSM-48, ZSM-57, ferrierite, ITQ-13, MCM-68 and MCM-71. Examples ofaluminophosphates containing at least one 10 ring channel includeECR-42. Examples of molecular sieves containing 12 ling channels includezeolite beta, and MCM-68. Some molecular sieves suitable for use hereinare described in U.S. Pat. Nos. 5,246,566, 5,282,958, 4,975,177,4,397,827, 4,585,747, 5,075,269 and 4,440,871. MCM-68 is described inU.S. Pat. No. 6,310,265. MCM-71 and ITQ-13 are described in PCTpublished applications WO 0242207 and WO 0078677. ECR-42 is disclosed inU.S. Pat. No. 6,303,534. Suitable SAPOs for use herein include SAPO-11,SAPO-31, SAPO-41, and suitable MAPOs include MAPO-11. SSZ-31 is also acatalyst that can be effectively used herein.

It is preferred that the catalytic hydrodewaxing catalyst used herein bea zeolite. Preferred zeolite catalytic hydrodewaxing catalysts suitablefor use herein include ZSM-48, ZSM-22 and ZSM-23. The molecular sievesare preferably in the hydrogen form.

Preferably, the catalytic hydrodewaxing catalyst selected would containa metal hydrogenation component and be bifunctional, i.e., they areloaded with at least one metal hydrogenation component, which isselected from Group VI metals, Group VIII metals, and mixtures thereof.Preferred metals are selected from Group VIII metals. Especiallypreferred are Group VIII noble metals such as Pt, Pd or mixturesthereof. These metals are loaded at the rate of 0.1 to 30 wt. %, basedon catalyst. Catalyst preparation and metal loading methods aredescribed for example in U.S. Pat. No. 6,294,077, and include forexample ion exchange and impregnation using decomposable metal salts.Metal dispersion techniques and catalyst particle size controltechniques are described in U.S. Pat. No. 5,282,958. Catalysts withsmall particle size and well-dispersed metal are preferred.

The molecular sieves are typically composited with binder materialswhich are resistant to high temperatures which may be employed underhydrodewaxing conditions to form a finished catalytic hydrodewaxingcatalyst or may be binderless (self bound). The binder materials areusually inorganic oxides such as silica, alumina, silica-aluminas,binary combinations of silicas with other metal oxides such as titania,magnesia, thoria, zirconia and the like and tertiary combinations ofthese oxides such as silica-alumina-thoria and silica-alumina magnesia.The amount of molecular sieve in the finished catalytic hydrodewaxingcatalyst is from 10 to 100, preferably 35 to 100 wt. %, based oncatalyst. Such catalysts are formed by methods such spray drying,extrusion and the like. The catalytic hydrodewaxing catalyst may be usedin the sulfided or unsulfided form, and is preferably in the sulfidedform for metal containing HDW catalyst.

The catalytic hydrodewaxing reaction stage used to produce lubebasestocks suitable for the present invention can be comprised of one ormore fixed bed reactors or reaction zones each of which can comprise oneor more catalyst beds of the same or different catalyst. Although othertypes of catalyst beds can be used, fixed beds are preferred. Such othertypes of catalyst beds include fluidized beds, ebullating beds, slurrybeds, and moving beds. Interstage cooling or heating between reactors,reaction zones, or between catalyst beds in the same reactor, can beemployed. A portion of any heat generated during catalytic hydrodewaxingcan be recovered. Where this heat recovery option is not available,conventional cooling may be performed through cooling utilities such ascooling water or air, or through use of a hydrogen quench stream. Inthis maimer, optimum reaction temperatures can be more easilymaintained.

Hydrogen-containing treat gasses suitable for use in the catalytichydrodewaxing reaction stage can be comprised of substantially purehydrogen or can be mixtures of other components typically found inrefinery hydrogen streams. However, it is preferred that thehydrogen-containing treat gas stream contains little, more preferablyno, hydrogen sulfide. The hydrogen-containing treat gas purity should beat least about 50% by volume hydrogen, preferably at least about 75% byvolume hydrogen, and more preferably at least about 90% by volumehydrogen for best results.

The contacting of the partially dewaxed fraction with the catalytichydrodewaxing catalyst results in a reaction product comprising at leasta gaseous product and a liquid product, wherein the liquid productcomprises a lube basestock suitable for use in the present invention.Thus, the process used to prepare lube basestocks suitable for useherein involves separating the catalytic hydrodewaxing stage reactionproduct into at least the gaseous product and the liquid productcomprising a lube basestock and recovering the liquid product comprisinga lube basestock. The means by which the catalytic hydrodewaxing stagereaction product is separated is not critical and may be performed byany means known to be effective at separating gaseous and liquidreaction products such as, for example, flash or knock-out drums orstripping.

The liquid product, comprising a lube basestock, recovered from thecatalytic hydrodewaxing reaction stage can be fractionated, by eithervacuum or atmospheric distillation, to provide various lube basestocksthat are suitable for use in a variety of formulated oils.

A lube oil boiling range feedstream, to be dewaxed according to thepreceding steps, may be treated in a number of processes.Hydroprocessing refers to processes in which hydrogen reacts with thelube oil boiling fraction under the influence of a catalyst.Non-limiting examples of hydroprocessing processes includehydrocracking; hydrotreating to remove heteroatoms, such as sulfur,nitrogen, and oxygen; hydrogenation of aromatics; hydroisomerizationand/or catalytic dewaxing; and demetallation of heavy streams.

The process used to prepare the lube basestock suitable for use hereincan further comprise solvent extracting a lube oil boiling rangefeedstock prior to the solvent dewaxing stage. Thus, in this example,the feedstream to the solvent dewaxing stage is an aromatics leanraffinate. A lubricating oil feedstock is extracted in a solventextraction zone with an extraction solvent under conditions effective atproducing an aromatics lean raffinate.

The solvent extraction process selectively dissolves the aromaticcomponents in an aromatics-rich extract solution while leaving the moreparaffinic components in the aromatics-lean raffinate solution.Naphthenes are distributed between the extract and raffinate phases.Typical solvents for solvent extraction include phenol, furfural andN-methyl pyrrolidone. By controlling the solvent to oil ratio,extraction temperature and method of contacting distillate to beextracted with solvent, one can control the degree of separation betweenthe extract and raffinate phases. The solvent extraction process,solvent, and process conditions used herein are not critical to theinstant invention and can be any solvent extraction process known.

The process used to prepare the one lube basestock suitable for useherein comprises first solvent extracting a lube oil boiling rangefeedstock prior to the first hydroprocessing reactor stage, as describedabove, and following this by the solvent dewaxing stage.

The above description is directed to preferred embodiments of thepresent invention. Those skilled in the art will recognize that otherembodiments that are equally effective could be devised for carrying outthe spirit of this invention.

The following examples will illustrate the improved effectiveness of thepresent invention, but is not meant to limit the present invention inany fashion.

EXAMPLES Example 1 Trim Catalytic Hydrodewaxing Using Zeolite Catalysts

The present invention was illustrated by comparing formulated engineoils comprising basestocks produced by the above-described processingsequence, i.e., solvent dewaxing followed by trim catalytichydrodewaxing using a zeolite catalyst with no metal hydrogenationfunction to others employing only solvent dewaxing. This dataillustrates the benefit of this invention using a zeolite catalyst totrim hydrodewax over the traditional approach of solvent dewaxing tolower target pour point. The properties of the catalysts used, and theamount employed, in the examples herein are outlined in Table 1 below.These catalysts included a non-metal HDW catalyst (H-ZSM-48/Al₂O₃)(“Catalyst B”). Catalyst B was formed into 1/16″ quadrulobe extrudatesthat contained 65% ZSM-48 crystals bound with 35% alumina. Catalyst Cwas formed using self-bound H-ZSM-5 extrudates.

TABLE 1 Trim Catalytic Hydrodewaxing Zeolite Catalyst PropertiesCatalyst Name Catalyst B Catalyst C H/Pt N/A N/A Support H-ZSM-48H-ZSM-5 Binder Al₂O₃ N/A Surface Area (m²/g) 239 N/A Alpha  20 47Catalyst Volume (cc)  5  5 Pre-sulfidation No No

HDW Reactor Preparation and Operating Procedure

A solvent dewaxed feedstream having the properties outlined in Table 2below was separately hydrodewaxed using Catalyst B and Catalyst C. Thetrim catalytic hydrodewaxing studies were performed using a continuouscatalyst testing unit composed of a liquid feed system with an ISCOsyringe pump, a fixed-bed tubular reactor with a three-zone furnace,liquid product collection, and an on-line MTI GC for gas analysis. 5-10cc, as outlined in Table 1, of catalyst was charged in a down-flow ⅜″stainless steel reactor containing a ⅛″ thermowell. After the unit waspressure tested, the catalyst was dried at 300° C. for 2 hours with 250cc/min N₂ at ambient pressure. If pre-sulfidation of the catalyst wasrequired, 2% (vol) H₂S in hydrogen was flowed through the catalyst bedat 100 sccm for 1 hour. Upon completion of the catalyst treatment, thereactor was cooled to 150° C., the unit pressure was set to 1000 psig byadjusting the Mity-Mite back-pressure regulator and the gas flow wasswitched from N₂ to H₂. The liquid solvent dewaxed feedstream describedin Table 2 was introduced into the reactor at the desired liquid hourlyspace velocity (LHSV). Once the liquid solvent dewaxed feedstreamreached the downstream knockout pot, the reactor temperature wasincreased to the target value. A material balance (MB) was initiateduntil the unit was lined out for 6 hours. The total liquid product (TLP)was collected in the MB dropout pot. Gas samples were analyzed with anon-line HP MTI gas chromatograph (GC) equipped with both TCD and FIDdetectors. A series of runs were performed to understand the catalystactivity/product properties as function of the process variables, suchas LHSV and process temperature. The TLP product from each balance wascut at 370° C. by batch distillation. The properties of 370+° C. dewaxedoil and wax were analyzed. The 370+° C. dewaxed oil was then blended asdescribed in the next section below.

TABLE 2 Solvent Dewaxed Feedstream Properties Density, g/cc 0.844Boiling Range 2% to 98% off, ° F. 690-910 Kinematic Viscosity at 40° C.,cSt 23.3 Kinematic Viscosity at 100° C., cSt 4.6 Viscosity Index 114Pour Point (ISL), ° C. −18 UV Total Aromatics, mmol/kg 18.5 SayboltColor >+30 GCD Noack Volatility, wt % 15.2 Sulfur, wppm <10 Nitrogen,wppm <1

Finished Oil Blending and Testing

The basestock produced by solvent dewaxing followed by catalytichydrodewaxing as described above was then blended to make a 5W-30 engineoil. The above basestock was a lighter viscosity than required for thefinished 5W-30 oil and hence a second basestock which was somewhatheavier was added to all the blends to hit a base oil desired viscositytarget. A commercial additive package for GF-3 engine oils was thenadded to make the formulated oil. This package consists of a detergentinhibitor package, a viscosity modifier, and a pour point depressant.The package utilized and the second basestock were constants in all theblends, only the light basestock was varied.

To determine whether zeolite catalysts are effective as trim catalytichydrodewaxing catalysts, it is useful to compare their performanceagainst trim solvent dewaxing samples. These trim solvent dewaxingsamples were processed by using the same feedstock and further solventdewaxing to lower target pour points. In this way, a direct comparisonis made between the efficacy of trim catalytic hydrodewaxing and trimsolvent dewaxing. The feedstock itself which has already beencommercially solvent dewaxed is also blended into the same 5W-30 packageto show the benefits of additional dewaxing whether by solvent orcatalytic hydrodewaxing. The data is shown in Table 3 below.

TABLE 3 Trim Solvent and HDW Basestock and Formulated 5W-30 Engine OilProperties (Catalyst B and C) HDW HDW Full Solvent Basestock BasestockPhysical Property Feed Dewaxing (Catalyst B) (Catalyst C) Density, g/cc0.844 0.811 0.811 Kinematic Viscosity at 40 C., cSt 23.3 23.16 23.3423.78 Kinematic Viscosity at 100 C., cSt 4.6 4.60 4.61 4.65 ViscosityIndex 114 114.3 113.1 112.8 Pour Point (ISL), deg C. −18 −20 −19 −20 GCDNoack Volatility, wt % 15.2 15.6 Kinematic Viscosity at 100 C.(formulated oil), cSt 10.26 10.39 10.35 10.38 CCS (formulated 5W30engine oil), cP 5790 4600 na na MRV (formulated 5W30 engine oil), YieldStress <35 <35 <35 <35 MRV (formulated 5W30 engine oil), cP 36211 3320029600 31400

As can be seen from the data, trim solvent dewaxing to about −20° C.pour point is effective in lowering the MRV viscosity from 36,211 cP to33,200 cP, a ˜8% reduction in MRV viscosity. This shows that it isfairly difficult for a solvent refinery to dramatically impact the MRVviscosity using only a small change in target pour point. Large changesin target pour point, while more effective, also involve much greateryield debits and chilling costs.

Using trim catalytic hydrodewaxing with the zeolite catalysts provideslarger benefits. Catalyst C lowered the MRV viscosity to 31,400 cP, a˜13% reduction in MRV viscosity. Catalyst B lowered the MRV to 29,600cP, a ˜18% reduction in MRV viscosity. Both of these zeolite catalystsshow performance advantages over the trim solvent dewaxing approach.However, these advantages were still relatively small and the ¹³C-NMRFree Carbon Index and Epsilon Carbon content were negligibly changed (asshown in Table 4). Decreases in the mole percent of total pendant groupsand the increase in the free carbon index all indicate that decreasedbranching, most likely due to cracking, occurred.

TABLE 4 ¹³C NMR Data of Trim-HDW Basestock (Catalyst B) Solvent DewaxedTrim-HDW Basestock NMR Measurement Feedstream (Catalyst B) EpsilonCarbons, mole % 13.66 13.64 Total Pendant Groups, mole % 6.25 6.17 #Side Chains/Molecule 2.3 2.3 Carbon # 36.7 37.7 Free Carbon Index 4.314.41

Because it was sometimes difficult to exactly hit a target pour pointexperimentally in our pilot plant reactors, and also to look at trends,we dewaxed to a range of target pour points. FIG. 1 shows the resultsover the range of solvent trim dewaxing studied and the range of trimcatalytic hydrodewaxing using Catalyst B and C. These curves clearlyindicate the advantage of trim catalytic hydrodewaxing over trim solventdewaxing.

Example 2 Trim Catalytic Hydrodewaxing Using Bifunctional Catalysts

The present invention was also illustrated by comparing formulatedengine oils comprising basestocks produced by another of theabove-described processing sequences, i.e., solvent dewaxing followed bytrim catalytic hydrodewaxing using a bifunctional catalyst with a metalhydrogenation function, to others employing trim catalytic hydrodewaxingusing the zeolite catalysts of Example 1. This data illustrates thefurther benefit of this invention using a bifunctional catalyst to trimhydrodewax over that shown in Example 1 of using a zeolite catalyst totrim hydrodewax. The properties of the catalysts used, and the amountemployed, in the examples herein are outlined in Table 5 below.

TABLE 5 Trim Catalytic Hydrodewaxing Bifunctional Catalyst PropertiesCatalyst Name Catalyst A Pt loading (%) 0.62 H/Pt 1.16 Support ZSM-48Binder Al₂O₃ Surface Area (m²/g) 247 Alpha 24 Catalyst Volume (cc) 10Pre-sulfidation Yes

Reactor Preparation and Operating Procedure

The same feed as shown in Table 2 of Example 1 was used in this example.The HDW reactor preparation and operating procedure is also as describedabove in Example 1 with the following conditions: T=270-345° C., P=1000psig, liquid rate=10 cc/hr, H₂ circulation rate=2500 scf/bbl, and LHSV=1hr⁻¹. The 370+° C. dewaxed oil was then collected and blended fortesting.

The 370° C.+ conversion of the solvent dewaxed feedstream was seen toincrease with increasing reactor temperatures. A low yield loss (<10%)could be achieved at a temperature range of 270 to 310° C. For obviousreasons, it is highly desirable to improve basestock properties whilemaximizing lube yield. At mild process conditions (process temperature @290° C.), the trim hydrodewaxed feedstream, sometimes referred to as alubricating oil basestock herein, showed a marginal decrease in pourpoint from −18° C. to −19° C., while 370° C.+ product yield loss wasonly about 3%, based on the solvent dewaxed feedstream. In addition, theviscosity index (“VI”) and viscosity remained nearly unchanged. Anadditional benefit of the present invention is that by using Catalyst A,a bifunctional catalyst, in the trim HDW mode is the aromatic saturationcapability of the catalyst. The aromatics content of the trim HDWproduct is essentially zero. High saturate content, i.e., saturatedaromatics, in the lube product provides better oxidation stability andincreases the value of the lube oil basestock. Table 6 summarizes thephysical properties of the lube fraction of the product with the highest370° C.+ yield.

TABLE 6 Trim HDW Basestock Properties (Catalyst A) Trim-HDW BasestockPhysical Property Feed (Catalyst A) 370° C.+ Yield, % on SDW feed 97.594.6 Kinematic Viscosity at 40° C., cSt 23.3 23.7 Kinematic Viscosity at100° C., cSt 4.6 4.7 Viscosity Index 114 113 Pour Point (ISL), ° C. −18−19 UV Total Aromatics, mmol/kg 18.5 0 Saybolt Color >+30 >+30 GCD NoackVolatility, wt % 15.2 15.3

Finished Oil Blending and Testing

The basestock produced by solvent dewaxing followed by catalytichydrodewaxing as described above was then blended to make a 5W-30 engineoil. The above basestock was a lighter viscosity than required for thefinished 5W-30 oil and hence a second basestock which was somewhatheavier was added to all the blends to hit a base oil desired viscositytarget. A commercial additive package for GF-3 engine oils was thenadded to make the formulated oil. This package consists of a detergentinhibitor package, a viscosity modifier, and a pour point depressant.The package utilized and the second basestock were constants in all theblends, only the light basestock was varied.

To assess the performance of bifunctional catalysts, they were comparedto other trim samples including the trim catalytic hydrodewaxing samplesof Example 1. The feedstock itself which has already been commerciallysolvent dewaxed is also blended into the same 5W-30 package to show thebenefits of additional trim dewaxing. The data generated using thebifunctional Catalyst A is shown in Table 7 below. The pilot plant runwas done twice; hence the first two columns used a basestock made in thefirst run and the third column used a basestock made in the second run.

TABLE 7 Trim HDW Basestock and Formulated 5W-30 Engine Oil Properties(Catalyst A) HDW (Catalyst HDW (Catalyst HDW (Catalyst Physical PropertyFeed A) A) A) Density, g/cc 0.844 0.810 0.810 Kinematic Viscosity at 40C., cSt 23.3 23.65 23.65 23.73 Kinematic Viscosity at 100 C., cSt 4.64.64 4.64 4.66 Viscosity Index 114 113.1 113.1 113.6 Pour Point (ISL),deg C. −18 −19 −19 −20 GCD Noack Volatility, wt % 15.2 KinematicViscosity at 100 C. (formulated oil), cSt 10.26 10.33 10.36 10.12 CCS(formulated 5W30 engine oil), cP 5790 5180 MRV (formulated 5W30 engineoil), Yield Stress <35 <35 <35 <35 MRV (formulated 5W30 engine oil), cP36211 19338 19536 19997

As can be seen from the data, trim catalytic hydrodewaxing to about −20°C. pour point is surprisingly effective in lowering the MRV viscosityfrom 36,211 cP to an average value of 19,624 cP, a 46% reduction in MRVviscosity. This level of MRV viscosity reduction under such mildcatalytic hydrodewaxing condition and with only small changes inbasestock bulk properties was much greater than expected. As summarizedin Table 6, minimal changes to basestock physical properties (viscosity,VI, pour point, volatility) were observed. Table 8 highlights the key¹³C NMR results of the feed versus trim HDW basestock. ¹³C NMR was usedto show that mild trim catalytic hydrodewaxing isomerizes the traceparaffins that impair the low temperature, low-shear properties ofsolvent-dewaxed basestocks to provide exceptional improvements toformulated engine oil cold flow properties. A substantial reduction tothe NMR Free Carbon Index from 4.31 to 4.02 was seen. Also a significantreduction to the NMR Epsilon Carbon content from 13.66 mole % to 13.04mole % was obtained. This confirms that a significant change to themolecular structure of the lube molecules was achieved withoutsignificant alteration to standard basestock physical properties.

TABLE 8 ¹³C NMR Data of Trim-Hydrodewaxed Basestock(Catalyst A) Trim-HDWBasestock NMR Measurement Feed (Catalyst A) Epsilon Carbons, mole %13.66 13.04 Total Pendant Groups, mole % 6.25 6.58 Pendant MethylGroups, mole % 5.00 5.30 # Side Chains/Molecule 2.3 2.4 Carbon # 36.736.5 Free Carbon Index 4.31 4.02

This 46% decrease in MRV and 11% decrease in CCS were obtained with lessthan 3% yield loss in mild trim-HDW with Catalyst A. As noted above, thearomatic saturation benefit of using the Catalyst A in a trim HDW modeis clearly reflected by the negligible aromatics content of the trimhydrodewaxed product. The MRV improvement and yield loss associated withthe trim HDW over Catalyst A are superior to the improvements observedin Example 1 where Catalyst B and C were employed in the trim HDW setupas demonstrated by the 46% MRV improvement with <3% yield loss. This wasachieved through an effective molecular re-arrangement that was achievedwith Catalyst A but not with Catalyst B and C as evidenced by the NMRmeasurements. This is discussed further below.

Increases in the mole percent of total pendant groups, mole percent ofpendant methyl groups, and number of side chains and the decreaseobserved in the mole percent of epsilon carbons and free carbon indexall indicate that increased branchiness of lube molecules, likely due toisomerization, has occurred. No significant changes in carbon number(CN) were observed. The trends shown in Table 8 indicate thatisomerization is likely the key mechanism behind the extensiveimprovement observed in engine oil low temperature properties usingCatalyst A in a mild trim catalytic hydrodewaxing. Thus, overall, thetrends in Table 4 are quite opposite to the trends observed in Table 8.The trends shown in Table 4 indicate that cracking is the likely the keymechanism behind the 17% improvement in MRV observed in engine oil lowtemperature properties using the Catalyst B in a mild trim catalytichydrodewaxing mode. Cracking is not as effective in altering themolecular structure as isomerization as evidenced by the NMR data.Cracking is also not as effective in improving the low temperaturequality as shown by the MRV data discussed above.

Because it was sometimes difficult to exactly hit a target pour pointexperimentally in our pilot plant reactors, and also to look at trends,we dewaxed to a range of target pour points. FIG. 2 shows the resultsover the range of trim catalytic hydrodewaxing using Catalysts A, B, C,D, and E. These curves clearly indicate the advantage of trim catalytichydrodewaxing using a bifunctional catalyst such as Catalyst A over trimcatalytic hydrodewaxing using a zeolite catalyst such as Catalyst B andC. This can be most readily seen by looking at the MRV viscosityobtained at similar pour points, especially those pour points closer tothe feed such as around −20° C.

This example illustrated the improvement in low-temperature propertiesachievable using trim catalytic hydrodewaxing of a solvent-dewaxedfeedstream at mild conditions with Catalyst A. This example alsodemonstrates that although trim HDW using Catalyst B and C improved thelow temperature property of the solvent dewaxed feedstream, the lowtemperature property improvement demonstrated by the present inventionemploying Catalyst A were superior to those obtained with Catalyst B.

¹³C NMR was used to show that mild trim catalytic hydrodewaxingisomerizes the trace paraffins that impair the low temperature,low-shear properties of solvent-dewaxed basestocks to provideexceptional improvements to formulated engine oil cold flow properties.Table 9 highlights the key ¹³C NMR results of the feed versus trim HDWbasestock.

TABLE 9 ¹³C NMR Data of Trim-Hydrodewaxed Basestock(Catalyst A) Trim-HDWBasestock NMR Measurement Feed (Catalyst A) Epsilon Carbons, mole %13.66 13.04 Total Pendant Groups, mole % 6.25 6.58 Pendant MethylGroups, mole % 5.00 5.30 # Side Chains/Molecule 2.3 2.4 Carbon # 36.736.5 Free Carbon Index 4.31 4.02

Increases in the mole percent of total pendant groups, mole percent ofpendant methyl groups, and number of side chains and the decreaseobserved in the mole percent of epsilon carbons and free carbon indexall indicate that increased branchiness of lube molecules, likely due toisomerization, has occurred. No significant changes in carbon number(CN) were observed. The trends shown in Table 6 indicate thatisomerization is likely the key mechanism behind the extensiveimprovement observed in engine oil low temperature properties usingCatalyst A in a mild trim catalytic hydrodewaxing. Thus, overall, thetrends in Table 4 are quite opposite to the trends observed in Table 6.The trends shown in Table 4 indicate that cracking is the likely the keymechanism behind the 17% improvement in MRV viscosity observed in engineoil low temperature properties using the Catalyst B in a mild trimcatalytic hydrodewaxing mode. Cracking is not as effective in alteringthe molecular structure as isomerization as evidenced by the NMR data.Cracking is also not as effective in improving the low temperaturequality as shown by the MRV viscosity data discussed above.

Example 3 Comparative Example of HDW Followed by SDW

To further explore the potential for improving the low temperaturequality of a finished lubricant, the study was extended beyond trimdewaxing. trim dewaxing utilizes a solvent dewaxing process to dewax awaxy feed so that the majority of wax is removed in this first process.The second step of trim dewaxing is then done on the nearly dewaxed feedand only removes or isomerizes small amounts of residual wax. Toidentify whether the balance of wax removal between the first processand second process could be modified, we extended the study to sampleswhich had only been partially or mildly dewaxed in the first stepleaving more residual wax for the second step to handle.

We also wanted to determine of catalytic hydrodewaxing first followed bysolvent dewaxing as the second process would be effective. The degree ofcatalytic hydrodewaxing in the first stage was varied to also look atthe impact of catalytic hydrodewaxing severity and solvent dewaxingseverity. That is the subject of this third example. The catalytichydrodewaxing catalyst used was Catalyst A.

The HDW reactor preparation and operating procedure is same as describedabove in Example 1.

SDW Lab Procedure

The lab solvent dewaxings were conducted using a single stage batchfiltration with the large Buchner funnel apparatus. This apparatus usesa 24-cm filtration area and has up to a 1.5 gallon oil/wax/solventslurry capacity. The solvent was a mixture of methyl ethyl ketone (MEK)and methyl isobutyl ketone (MIBK).

As the filtration proceeds, the predominately wax component is left onthe surface of the filtration media, with the filtrate (oil and solvent)passing through the filter into a collection flask. These two productsare then stripped of their respective solvents using a rotary vacuumstripper to complete the filtration process. The DWO and wax werefurther analyzed to determine their individual physical properties.

The feed used in this case was a waxy light feedstream from the refineryand was a slightly lower viscosity grade than in Example 1 and 2.

TABLE 10 HDW Followed by SDW Basestock and Formulated 5W-30 Engine OilProperties Using Various Degrees of HDW to SDW HDW to 30, HDW to 13, HDWto −7, Physical Property Base Case SDW to −18 SDW to −19 SDW to −20Density, g/cc 0.844 Kinematic Viscosity at 40 C., cSt 23.3 18.91 18.46217.82 Kinematic Viscosity at 100 C., cSt 4.6 4.09 4.04 3.97 ViscosityIndex 114 117.1 118.210086 120.6 Pour Point (ISL), deg C. −18 −18 −19−20 GCD Noack Volatility, wt % 15.2 Kinematic Viscosity at 100 C.(formulated oil), cSt 10.26 10.28 10.27 10.26 CCS (formulated 5W30engine oil), cP 5790 6483 5227 MRV (formulated 5W30 engine oil), YieldStress <35 <175 <175 <175 MRV (formulated 5W30 engine oil), cP 36211103488 102578 92649

In this comparative example, the formulated oil MRV viscosity valuesmeasured were undesirable (Shown in Table 10). The base case fullsolvent dewaxed sample to −18° C. pour point gave a 5W-30 MRV viscosityof 36,211 cP with No Yield Stress (<35 Pa). The mildest HDW example wasHDW to +30° C. followed by SDW to −18° C., which is a very similar pourpoint to the base case. The 5W-30 MRV viscosity was 103,488 cP, muchhigher than base case, and a Yield Stress of <175 Pa was found. Thusthis formulated oil fails the MRV viscosity specifications on bothapparent viscosity and yield stress. The intermediate HDW example wasHDW to +13° C. followed by SDW to −19° C., which is a very similar pourpoint to the base case. The 5W-30 MRV viscosity was 102,578 cP, againmuch higher than the base case, and a yield stress of <175 Pa was found.Thus this formulated oil again fails the MRV viscosity specifications onboth apparent viscosity and yield stress. The most severe HDW examplewas HDW to −7° C. followed by SDW to −20° C., which is a very similarpour point to the base case. The 5W-30 MRV apparent viscosity was 92,649cP, again much higher than the base case, and a yield stress of <175 Pawas found. Thus this formulated oil again fails the MRV viscosityspecifications on both apparent viscosity and yield stress.

In all three cases, the NMR results help to explain the MRV viscosityresults seen. The Free Carbon Index has risen to 4.85 to 5.02% and theEpsilon Carbon content has increased to 15.35 mole % to 16.30 mole %.This is a comparative example that shows that when the NMR Free CarbonIndex and Epsilon Carbon contents exceed 4.3 and 14%, respectively, thelow temperature quality of the finished oil as demonstrated by the MRVviscosity deteriorates.

Thus, it is shown that HDW followed by SDW to an acceptable pour pointis unable to achieve acceptable finished oil low temperature quality.Even when the first HDW step is done to within about 11° C. of thedesired target, it is still not sufficient to generate good qualityproduct.

To look at trends going to lower pour points, the final SDW step wastaken to lower target pour points and the data is plotted in FIG. 3below. It can be seen that even at lower final pour points of −23 and−24° C., HDW followed by SDW is still not competitive with full SDWperformance.

Example 4 SDW Followed by HDW

To further explore the potential for improving the low temperaturequality of a finished lubricant, the study was extended beyond trimdewaxing. trim dewaxing utilizes a solvent dewaxing process to dewax awaxy feed so that the majority of wax is removed in this first process.The second step of trim dewaxing is then done on the nearly dewaxed feedand only removes or isomerizes small amounts of residual wax. Toidentify whether the balance of wax removal between the first processand second process could be modified, we extended the study to sampleswhich had only been partially or mildly dewaxed in the first stepleaving more residual wax for the second step to handle.

In this example, the first step is a Solvent Dewaxing Process to variousintermediate pour points followed by Catalytic hydrodewaxing usingCatalyst A to the final target pour points.

The feed used in this case was a waxy light feedstream from a refineryand was a slightly lower viscosity grade than in Example 1 and 2 and thesame feedstream as used in Example 3.

TABLE 11 SDW Followed by HDW Basestock and Formulated 5W-30 Engine OilProperties Using Various Degrees of SDW to HDW SDW to 10, SDW to −2,Physical Property Base Case HDW to −21 HDW to −19 Density, g/cc 0.8440.801 0.803 Kinematic Viscosity at 40 C., cSt 23.3 18.28 18.88 KinematicViscosity at 100 C., cSt 4.6 4.01 4.09 Viscosity Index 114 117.5 117.5Pour Point (ISL), deg C. −18 −21 −19 GCD Noack Volatility, wt % 15.2Kinematic Viscosity at 100 C. (formulated oil), cSt 10.26 10.26 10.28CCS (formulated 5W30 engine oil), cP 5790 4950 5126 MRV (formulated 5W30engine oil), Yield Stress <35 <35 <35 MRV (formulated 5W30 engine oil),cP 36211 17873 22826

In this example, the formulated oil MRV viscosity values were muchbetter than the base case (shown in Table 11). The base case fullsolvent dewaxed sample to −18° C. pour point gave a 5W-30 MRV viscosityof 36,211 cP with no yield stress (<35 Pa). The milder SDW example wasSDW to +10° C. followed by SDW to −21° C., which is a very similar pourpoint to the base case. The 5W-30 MRV viscosity was 17,873 cP, which is51% lower than the base case with no Yield Stress (<35 Pa). The moreintermediate SDW example was SDW to −2° C. followed by HDW to −19° C.,which is a very similar pour point to the base case. The 5W-30 MRVviscosity was 22,826 cP, which is 37% lower than the base case, and noYield Stress (<35 Pa) was found. The most severe SDW example is the trimcases discussed in Examples 1 and 2. Example 2 also used Catalyst A andthe 5W-30 MRV viscosity average value was 19,624 cP which was a 46%reduction and the benefit magnitude is very similar to what is shownhere.

Again, in all three cases, the NMR results help to explain the MRVviscosity results seen. The Free Carbon Index has dropped to 4.09 to4.29% and the Epsilon Carbon content has decreased to 13.67 mole % to13.72 mole %. This shows that when the NMR Free Carbon Index and EpsilonCarbon contents decrease below 4.3 and 14%, respectively, the lowtemperature quality of the finished oil as demonstrated by the MRVviscosity improves.

Thus, it is shown that SDW followed by HDW to an acceptable pour pointis a surprisingly effective means to achieve acceptable finished oil lowtemperature quality. This large benefit is seen independent of therelative amount of SDW to HDW. It seems critical that the final step beHDW but whether the SDW is run quite mild to higher pour points are runmore severely to lower pour points does not impact how effective thisprocessing approach is in impacting finished oil low temperaturequality.

To look at trends going to lower pour points, the final HDW step wastaken to lower target pour points and the data is plotted in FIG. 4below. It can be seen that as the final pour point is lowered, thebenefits continue until a final MRV viscosity of 10,000 -15,000 cP isreached.

1. A dewaxed lube basestock having a Free Carbon Index of less than 4.3and an Epsilon Carbon mole % of less than 14%.
 2. A dewaxed lubebasestock having a Free Carbon Index of less than 4.1 and an EpsilonCarbon mole % of less than 13.3%.
 3. A dewaxed lube basestock having aFree Carbon Index of from 3.0 to 4.3 and a Epsilon Carbon mole % from10.0% to 14.0%.
 4. A dewaxed lube basestock according to claim 1 whereinthe Pour Point is between −6° C. and −30° C.
 5. A dewaxed lube basestockaccording to claim 2 wherein the Pour Point is between −6° C. and −30°C.
 6. A dewaxed lube basestock according to claim 1 wherein the PourPoint is between −15° C. and −24° C.
 7. A dewaxed lube basestockaccording to claim 2 wherein the Pour Point is between −15° C. and −24°C.
 8. A dewaxed lube basestock according to claim 1 wherein thekinematic viscosity at 100° C. is between 3 cSt and 7 cSt, the ViscosityIndex is between 95 and 150, and the Pour Point is between −6° C. and−30° C.
 9. A dewaxed lube basestock according to claim 1 wherein thekinematic viscosity at 100° C. is between 3 cSt and 7 cSt, the ViscosityIndex is between 100 and 120, and the Pour Point is between −15° C. and−24° C.
 10. A dewaxed lube basestock according to claim 2 wherein thekinematic viscosity at 100° C. is between 3 cSt and 7 cSt, the ViscosityIndex is between 100 and 120, and the Pour Point is between −15° C. and−24° C.
 11. A dewaxed lube basestock according to claim 1 wherein thekinematic viscosity at 100° C. is between 4 cSt and 5 cSt, the ViscosityIndex is between 100 and 120, and the Pour Point is between −15° C. and−24° C.
 12. A dewaxed lube basestock having a Free Carbon Index of lessthan 4.3 and an Epsilon Carbon mole % of less than 14% prepared by aprocess comprising a) solvent dewaxing a lube oil boiling rangefeedstream in a solvent dewaxing stage operated under effective solventdewaxing conditions thereby producing at least a partially dewaxedfraction; and b) contacting said partially dewaxed fraction with ahydrodewaxing catalyst in the presence of a hydrogen-containing treatgas in a reaction stage operated under effective hydrodewaxingconditions thereby producing a reaction product comprising at least agaseous product and liquid product, wherein said liquid productcomprises a dewaxed lube basestock.
 13. A dewaxed lube basestockaccording to claim 12 wherein said hydrodewaxing catalyst is selectedfrom ZSM-5, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, Beta, SSZ-31,SAPO-11, SAPO-31, SAPO-41, MAPO-11, ECR-42, fluorided alumina,silica-alumina, fluorided silica alumina, synthetic Ferrierites,Mordenite, Offretite, Erionite, Chabazite, and mixtures thereof undereffective catalytic dewaxing conditions.
 14. A dewaxed lube basestockaccording to claim 13 wherein said hydrodewaxing catalyst comprises azeolite selected from ZSM-48, ZSM-22 and ZSM-23.
 15. A dewaxed lubebasestock according to claim 14 wherein said hydrodewaxing catalystfurther comprises at least one metal hydrogenation component, which isselected from Group VI metals, Group VIII metals, or mixtures thereofand contains at least one Group VIII noble metal.
 16. A formulated oilcomprising: a) a major amount of at least one dewaxed lube basestockaccording to claim 4, b) at least one component selected fromdispersants, detergents, wear inhibitors, antioxidants, rust inhibitors,demulsifiers, extreme pressure agents, friction modifiers, multifunctionadditives, viscosity index improvers, pour point depressants, and foaminhibitors.
 17. A formulated oil according to claim 16 wherein theformulated oil is an engine oil.
 18. An engine oil according to claim 17wherein said engine oil has a Mini Rotary Viscometer viscosity fromabout 10,000 cP to about 30,000 cP.
 19. An engine oil according to claim17 wherein said engine oil has a Mini Rotary Viscometer viscosity fromabout 10,000 cP to about 25,000 cP.
 20. An engine oil according to claim17 wherein said engine oil has a Mini Rotary Viscometer viscosity fromabout 12,000 cP to about 20,000 cP.
 21. An engine oil comprising: a) atleast 60% by weight of the total composition of a dewaxed lube basestockhaving a Free Carbon Index of from 3.0 to 4.3 and an Epsilon Carbon mole% from 10.0% to 14.0% and wherein the kinematic viscosity at 100° C. isbetween 3 cSt and 7 cSt, the Viscosity Index is between 95 and 150, andthe Pour Point is between −6° C. and −30° C. b) at least one componentselected from dispersants, detergents, wear inhibitors, antioxidants,rust inhibitors, demulsifiers, extreme pressure agents, frictionmodifiers, multifunction additives, viscosity index improvers, pourpoint depressants, and foam inhibitors, and wherein the said engine oilhas a Mini Rotary Viscometer viscosity from about 10,000 cP to about25,000 cP.
 22. An engine oil comprising: a) at least 60% by weight ofthe total composition of a dewaxed lube basestock having a Free CarbonIndex of from 3.0 to 4.3 and an Epsilon Carbon mole % from 10.0% to14.0% and wherein the kinematic viscosity at 100° C. is between 3 cStand 7 cSt, the Viscosity Index is between 95 and 150, and the Pour Pointis less than −6° C. and wherein said dewaxed lube basestock is preparedby a process comprising (i) solvent dewaxing a lube oil boiling rangefeedstream in a solvent dewaxing stage operated under effective solventdewaxing conditions thereby producing at least a partially dewaxedfraction; and (ii) contacting said partially dewaxed fraction with ahydrodewaxing catalyst in the presence of a hydrogen-containing treatgas in a reaction stage operated under effective hydrodewaxingconditions thereby producing a reaction product comprising at least agaseous product and liquid product, wherein said liquid productcomprises a dewaxed lube basestock. b) at least one component selectedfrom dispersants, detergents, wear inhibitors, antioxidants, rustinhibitors, demulsifiers, extreme pressure agents, friction modifiers,multifunction additives, viscosity index improvers, pour pointdepressants, and foam inhibitors, and wherein the said engine oil has aMini Rotary Viscometer viscosity from about 10,000 cP to about 25,000cP.
 23. An engine oil comprising: a) at least 60% by weight of the totalcomposition of a dewaxed lube basestock having a Free Carbon Index offrom 3.0 to 4.3 and an Epsilon Carbon mole % from 10.0% to 14.0% andwherein the kinematic viscosity at 100° C. is between 3 cSt and 7 cSt,the Viscosity Index is between 95 and 150, and the Pour Point is lessthan −6° C. and wherein said dewaxed lube basestock is prepared by aprocess comprising (i) solvent dewaxing a lube oil boiling rangefeedstream in a solvent dewaxing stage operated under effective solventdewaxing conditions thereby producing at least a partially dewaxedfraction; and (ii) contacting said partially dewaxed fraction with ahydrodewaxing catalyst in the presence of a hydrogen-containing treatgas in a reaction stage operated under effective hydrodewaxingconditions thereby producing a reaction product comprising at least agaseous product and liquid product, wherein said liquid productcomprises a dewaxed lube basestock. b) at least one component selectedfrom dispersants, detergents, wear inhibitors, antioxidants, rustinhibitors, demulsifiers, extreme pressure agents, friction modifiers,multifunction additives, viscosity index improvers, pour pointdepressants, and foam inhibitors, and wherein the said engine oil has aMini Rotary Viscometer viscosity from about 10,000 cP to about 25,000cP.
 24. A method of formulating an engine oil comprising blending adewaxed lube basestock as characterized in claim 6 with at least onecomponent selected from dispersants, detergents, wear inhibitors,antioxidants, rust inhibitors, demulsifiers, extreme pressure agents,friction modifiers, multifunction additives, viscosity index improvers,pour point depressants, and foam inhibitors.